1. Technology Field
The invention relates to a method for managing data which are stored in a non-volatile random access memory (NVRAM) and a volatile random access memory (VRAM) and a memory storage device and a memory control circuit unit using the method.
2. Description of Related Art
The rapid growth of digital cameras, mobile phones, and MP3 players in recent years leads to a drastic increase in consumers' demand for storage media. A rewritable non-volatile memory module (e.g., a flash memory) is suitable for being embedded in the aforementioned exemplary portable multimedia devices due to having characteristics, such as data non-volatility, low power consumption, small volume, and non-mechanical structure. Generally, non-volatile memory module is operated along with a volatile random access memory (VRAM). For instance, when data is to be written from a host system to a non-volatile memory module, such data is first written into the VRAM and then written into the non-volatile memory module. Through a proper mechanism for data management, the combination of the non-volatile memory module and the VRAM can effectively enhance overall data access speed and operation flexibility.
However, if a power supply problem such as sudden power failure or unstable voltage supply occurs during the process of writing the data from the VRAM to the non-volatile memory module, the data stored in the VRAM may probably be lost, and as a result, the data can not be completely written into the non-volatile memory module. Therefore, some units or individuals may choose to additionally install an uninterruptible power supply (UPS) or a supercapacitor for transferring or backing up a portion of the data in a short time when the power supply problem occurs, for example, all of the data stored in the VRAM is backed up in the non-volatile memory module for reducing loss. However, the maintenance of UPS costs high, and the time for the UPS or the super capacitor supplying the power can not last long, which leads to inconvenience in usage.
Nothing herein should be construed as an admission of knowledge in the prior art of any portion of the invention. Furthermore, citation or identification of any document in this application is not an admission that such document is available as prior art to the invention, or that any reference forms a part of the common general knowledge in the art.